A Viral Protein Restricts Drosophila RNAi Immunity by Regulating Argonaute Activity and Stability.

A Viral Protein Restricts Drosophila RNAi Immunity by Regulating Argonaute Activity and Stability.

Cell host & microbe (2018-10-12)

Arabinda Nayak, Dong Young Kim, Michael J Trnka, Craig H Kerr, Peter V Lidsky, David J Stanley, Brianna Monique Rivera, Kathy H Li, Alma L Burlingame, Eric Jan, Judith Frydman, John D Gross, Raul Andino

PMID30308158

ABSTRACT

The dicistrovirus, Cricket paralysis virus (CrPV) encodes an RNA interference (RNAi) suppressor, 1A, which modulates viral virulence. Using the Drosophila model, we combined structural, biochemical, and virological approaches to elucidate the strategies by which CrPV-1A restricts RNAi immunity. The atomic resolution structure of CrPV-1A uncovered a flexible loop that interacts with Argonaute 2 (Ago-2), thereby inhibiting Ago-2 endonuclease-dependent immunity. Mutations disrupting Ago-2 binding attenuates viral pathogenesis in wild-type but not Ago-2-deficient flies. CrPV-1A also contains a BC-box motif that enables the virus to hijack a host Cul2-Rbx1-EloBC ubiquitin ligase complex, which promotes Ago-2 degradation and virus replication. Our study uncovers a viral-based dual regulatory program that restricts antiviral immunity by direct interaction with and modulation of host proteins. While the direct inhibition of Ago-2 activity provides an efficient mechanism to establish infection, the recruitment of a ubiquitin ligase complex enables CrPV-1A to amplify Ago-2 inactivation to restrict further antiviral RNAi immunity.

MATERIALS

Product Number

Brand

Product Description

F3165

Sigma-Aldrich

Monoclonal ANTI-FLAG^® M2 antibody produced in mouse, clone M2, purified immunoglobulin (Purified IgG1 subclass), buffered aqueous solution (10 mM sodium phosphate, 150 mM NaCl, pH 7.4, containing 0.02% sodium azide)

69041

Sigma-Aldrich

B834(DE3) Competent Cells - Novagen, B834 is the parental strain for BL21. These hosts are methionine auxotrophs and allow high specific activity labeling of target proteins with 35S-methionine and selenomethionine for crystallography.